MRA can
find problems with the blood vessels that may be causing reduced blood flow.
With MRA, both the blood flow and the condition of the blood vessel walls can
be seen. The test is often used to look at the blood vessels that go to the
brain, kidneys, and legs. Information from an MRA can be saved and stored on a
computer for further study. Photographs of selected views can also be made.

During MRA, the area of the body
being studied is placed inside an MRI machine.
Contrast material is often used during MRA to make
blood vessels show up more clearly.

Why It Is Done

A magnetic resonance angiogram (MRA)
is done to look for:

A bulge (aneurysm),
clot, or the buildup of fat and calcium deposits (stenosis caused by plaque) in
the blood vessels leading to the brain.

An aneurysm or tear (dissection) in the
aorta, which carries blood from the heart to the rest
of the body.

Narrowing (stenosis) of the blood vessels leading to
the heart, lungs, kidneys, or legs.

How To Prepare

Before a magnetic resonance angiogram
(MRA), tell your doctor and the MRI technologist if you:

Are allergic to any medicines. The contrast
material used for MRA does not contain iodine. If you know that you are
allergic to the contrast material used for MRA, tell your doctor before having
another test.

Are or might be pregnant.

Have any metal implanted in your body. This information helps your doctor know if the test is safe for you. Tell your doctor if you have:

Metal pins, clips, or metal parts in your body, including artificial limbs and dental work or braces.

Any other implanted medical device, such as a
medicine infusion pump.

Cosmetic metal implants, such as in your ears.

Have an
intrauterine device (IUD) in place. An IUD may prevent
you from having the MRA test done.

Become very nervous in small
spaces. You need to lie very still inside the MRI machine, so you may need to
have the test done with open MRI equipment. It is not as confining as standard
MRI machines. You may need medicine to help you relax. Some blood vessels may
not be seen clearly with an open MRI scanner.

Have any other health
conditions, such as kidney problems or
sickle cell anemia, that may prevent you from having
an MRA using contrast material.

Wear any medicine patches. The MRI may cause a burn at the patch
site.

For some abdominal MRI tests, you may be asked to not eat
or drink before the test.

You may need to arrange for someone to
drive you home after the test, if you are given a medicine (sedative) to help you relax.

If you are
having blood flow studies, do not use tobacco products and do not eat or drink (including
alcohol or caffeinated beverages) for 2 hours before the test. Do not take iron
supplements on the day of the test.

You may be asked to sign a consent form that says you understand the risks of the test and agree to have it done.

Talk to your
doctor about any concerns you have regarding the need for the
test, its risks, how it will be done, or what the results will mean. To
help you understand the importance of this test, fill out the
medical test information form(What is a PDF document?).

How It Is Done

A magnetic resonance angiogram (MRA)
test is usually done by a magnetic resonance image (MRI) technologist. The test
is done in an
MRI machine. The resulting pictures are usually interpreted by a
radiologist. But some other types of doctors can also
interpret an MRA scan.

Before the test

Remove all metal objects, such as hearing aids,
dentures, jewelry, watches, hairpins, wigs, and eyeglasses, from your body
because these objects may be attracted to the powerful magnet used for the
test. If you have had a car crash or an accident while working with metal, it is possible that you have metal fragments in your head, eyes, skin,
or spine. An X-ray may be taken before the MRA to see if you can have the
test.

Take off all or most of your clothes, depending on which area
is examined. You may be allowed to keep on your underwear if it does not get in
the way. You will be given a cloth or paper covering to use during the
test.

You may be given a sedative if you are nervous or you do not
think you can lie still for the test.

During the test

You will lie on your back on a table that is
part of the MRI scanner.

If you are cold or uncomfortable, you may
want to ask for a pillow or blanket.

Your head, chest, and arms may
be held with straps to help you remain still.

The table will slide
into a space that contains the magnet. Depending on the part of your body to be
examined, your head, limbs (such as your legs), or your entire body will be
moved into the center of the magnet.

Inside the scanner, you may hear a fan and feel air moving.
You may also hear tapping or thumping noises as the MRA scans are taken. You
may want to ask for ear plugs to reduce the noise.

It is important
to hold completely still while the scan is being done. Otherwise, repeat scans
may be needed.

You may be asked to hold your breath for short
periods of time.

You may be alone in the scanner room. But the
technologist will watch you through an observation window, and you will be able
to talk to him or her through an intercom.

If contrast material is needed, the technologist will put
it in an
IV in your arm. The material may be given over 1 to 2
minutes. Then more MRI scans are done.

An MRA test usually takes
30 to 90 minutes but can take as long as 2 hours.

How It Feels

You won't have pain from the magnetic
field or radio waves used for the MRI test. The table you lie on may feel hard
and the room may be cool. You may be tired or sore from lying in one position
for a long time.

Some people feel discomfort or anxiety
(claustrophobia) inside the MRI magnet. If this keeps you from lying still, you
can be given a sedative to help you relax. Open MRI machines are less confining
than standard MRI and may be helpful if you are claustrophobic.

If
a contrast material is used, you may feel some coolness when it is
put into your IV. In rare cases, you may feel:

A tingling feeling in the mouth if you have
metal dental fillings.

Warmth in the area being examined. This is
normal. Tell the technologist if you have nausea, vomiting, headache,
dizziness, pain, burning, or breathing problems.

Risks

There is a slight risk of having an
allergic reaction if
contrast material is used during the MRA scan. Most
reactions can be controlled using medicine.

An MRI can cause a
burn with some medicine patches. Be sure to tell your doctor if you are wearing
a patch.

If you have kidney
disease, such as kidney failure, talk to your doctor before having an MRA scan
with contrast material. The contrast material used for an MRA contains a
chemical called gadolinium. If you have kidney disease, this chemical may cause
a serious problem, called nephrogenic systemic fibrosis.

If you breastfeed and are concerned about whether the dye used in this test is safe, talk to your doctor. Most experts believe that very little dye passes into breast milk and even less is passed on to the baby. But if you prefer, you can store some of your breast milk ahead of time and use it for a day or two after the test.

Results

A magnetic resonance angiogram (MRA) is
a type of
magnetic resonance imaging (MRI) scan that uses a
magnetic field and pulses of radio wave energy to provide pictures of blood
vessels inside the body. The
radiologist may talk to you about the results of your
MRA right after the test. Complete results are usually available for your
doctor in 1 to 2 days.

Magnetic resonance angiogram (MRA)

Normal:

The blood vessels look normal and the blood
flow through them is not reduced or stopped. No blood clots or large
plaque buildup is seen.

Blood vessel walls are normal. No bleeding,
abnormal collections of fluid, blockage in the flow of blood, or bulges in the
blood vessels (aneurysms) are present.

Abnormal:

Partial or complete blockage of a blood
vessel may be seen. Blockage may be caused by a blood clot, the buildup of fat
and calcium deposits (plaque), or narrowing (stenosis) of the blood
vessel.

A bulge (aneurysm) in the blood vessel wall
may be seen. Damage to the wall of a blood vessel may be seen.

Conventional angiogram or
a CT angiogram (computed tomography angiogram) may
be needed after MRA if a problem, such as an aneurysm, is found or if surgery
may be needed.

What Affects the Test

Reasons you may not be able to
have the test or why the results may not be helpful include:

Pregnancy. Although the strong magnetic field
used for an MRA does not appear to be harmful, MRA usually is not done when you
are pregnant. If a view of your belly is needed and you are pregnant, an
ultrasound test may be done instead.

You
are using a medical device that contains metal, such as an
IUD, a pacemaker, some types of artificial limbs, or
medicine infusion pumps. These devices can malfunction or cause problems during
an MRA scan.

Not being able to lie still during the test. The
results of MRA may not be accurate if you can't remain still during the
test.

Being overweight and not fitting into the opening of some MRI
scanners.

What To Think About

While MRA is a safe and valuable test for
looking at blood vessels inside the body, it is more expensive than other
imaging techniques, and it may not be available in all medical
centers.

An advantage of MRA is that no radiation is
involved.

You may be able to have your MRA in an open MRI machine that doesn't enclose your entire body. But open MRI machines aren't available everywhere. The pictures from an open MRI may not be as good as those from a standard MRI machine. Also,
these machines may not be able to do all the studies needed to check for
problems.

Open MRI is useful for people who are
claustrophobic or obese.

Conventional angiogram or a CT angiogram (computed tomography angiogram) may be done to double-check abnormal results from the
MRA in some types of blood vessels such as the aorta. These tests might be an
option especially if surgery is being considered to treat the
problem.

MRA results may show an aneurysm is present when it is
not (false-positive). It also may show no aneurysm when one
is present (false-negative). MRA is most accurate for larger blood
vessels.

References

Other Works Consulted

Bluemke, D, et al. (2008). Noninvasive coronary artery imaging: Magnetic resonance angiography and multidetector computed tomography angiography. A scientific statement From the American Heart Association Committee on Cardiovascular Imaging and Intervention of the Council on Cardiovascular Radiology and Intervention, and the Councils on Clinical Cardiology and Cardiovascular Disease in the Young. Circulation, 118: 586–606.

Levine GN, et al. (2007). Safety of magnetic resonance imaging in patients with cardiovascular devices: An American Heart Association scientific statement from the Committee on Diagnostic and Interventional Cardiac Catheterization, Council on Clinical Cardiology, and the Council on Cardiovascular Radiology and Intervention: Endorsed by the American College of Cardiology Foundation, the North American Society for Cardiac Imaging, and the Society for Cardiovascular Magnetic Resonance. Circulation, 116(24): 2878–2891.

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